Detective Tsuda, Episode 4: The Electric Trap and a 100-Year Prayer Part 2 Atsuhiro Tsuda and Minamikawa travel 100 years back in time via a time machine to investigate the mystery surrounding the Edajima family tree. There, they discover that, for some reason, Rika's mother, Ume, married the servant Tamasuke according to the family registry, and that Rika's surname is also "Yamada". Tsuda closes in on the truth of the case from the events that transpired between the two families.